In an application of this type, a central control unit and a plurality of electronic modules are connected to the network for the purposes:                firstly of making it possible to implement remote control or remote parameter setting; and        secondly of transferring to a central station information that has been detected by the electronic modules.        
As a general rule, an electricity distribution network presents topology that is complex, including numerous intersections that are randomly distributed. Furthermore, knowledge of the exact topology of the network has often been lost, with such a network generally being the result of successive installation operations performed over several tens of years.
Furthermore, carrier current transmission range is relatively short. It is therefore necessary for the transmitted messages to be repeated in order to enable them to reach their destinations.
In particular, the electricity distribution network presents a wide variety of impedances as a function of location and as a function of the users that are connected to the network.
Furthermore, the types of cable used (overhead, twisted, buried, single-phase, or three-phase) vary very often as a function of circumstances and the impedances per unit length specific to each type of cable, which impedances are likewise very variable.
Thus, when using the carrier current technique, in application of present standards, and insofar as it is desired to transmit data over long distances over an electricity network, it is essential to have a system for regenerating messages.
Because the impedances and attenuations are not under control, it is difficult to determine in advance which modules ought to reamplify messages.
Furthermore, if it is desired to be able to communicate with each module separately, it is necessary for each module to be given its own address.
In the context of such a network, giving each module an address raises numerous problems.
Firstly, it is necessary for the addressing mode of the various modules that are to be enabled to communicate can be applied to a network of any topology. Then, if it is desired to interconnect a large number of modules, it must be possible to perform module addressing without time-consuming operations that would involve a high risk of error. Provision must also be made for it to be easy to add a module to the network without that requiring manual intervention on other modules.
French patent No. 95/05749 proposes an addressing mode that requires manual action to be performed on each module that does not yet have an address and also on the module that does have an address and that is situated immediately upstream going towards a central unit situated at the root of the tree structure network. The address of the module that does not yet have an address is determined as a function of the address of the upstream module. That method thus presents the drawback of requiring operators to intervene on site by acting on control buttons provided on each module.
French patent No. 00/01559 proposes a method of automatically allocating addresses, in which the address of each module is determined from the address of the module situated immediately upstream, said address being sent over the network by the upstream module in an address allocation message. That method enables excellent results to be obtained, however it is difficult to implement and is not well suited to a network that is relatively complex.